1. Field of the Invention
The present invention relates to an Escherichia species microorganism or Corynebacterium species microorganism including a foreign NADP dependent glyceraldehydes-3-phosphate dehydrogenase gene and a method of producing L-lysine using the same.
2. Description of the Related Art
L-lysine is a kind of amino acid widely used for feed and medical supplies and is produced on an industrial scale using microorganisms. L-lysine has been produced by fermentation with strains, for example, Corynebacterium, especially Corynebacterium glutamicum. However, to compensate for disadvantages of Corynebacterium, it has been tried to use other microorganisms, for example, Escherichia coli. (E. coli). Escherichia coli is a gram negative microorganism that is scientifically and industrially most widely used. Since much research has been performed on E. coli by many researchers, and a larger amount of information on E. coli than on Corynebacterium is accumulated. An advantage of E. coli lies in that it is easy to handle the strain in a fermentation process. Therefore, research on the production of a large amount of L-amino acid using a wild type E. coli has been performed.
There has been research on an effect of the amplification of a L-lysine biosynthesis-related gene using a recombinant DNA technology on the synthesis of L-lysine and research on the improvement of L-lysine producing E. coli strain (EP0733710A1 and EP0723011 A1). For example, EP1253195A1 (Ajinomoto Co., Inc.) discloses that the productivity of lysine increases when the activity of enzyme, such as aspartate semialdehyde dehyrogenase, phosphoenolpyruvate carboxylase, transhydrogenase, and aspartase, increases. In addition, EP0733710A1 discloses a bacterium having mutant genes of dapA and lysC genes and further enhanced with dapB gene and a ddh gene.
Glyceraldehyde-3-phosphate dehydrogenases (GAPDH) involved in the in vivo carbon metabolism include a NAD dependent GAPDH acting in glycolysis, an NADP dependent GAPDH, and a nonphosphorylation NADP-dependent □lyceraldehydes-3-phosphate dehydrogenase (GapN) (Iddar, A, et al., Protein Expr Purif. 25(3): 519-26 (2002)). L-lysine in E. coli is synthesized from L-aspartate through 9 enzymatic reaction steps, two of which are NADPH-dependent steps. The concentration of NADPH in cell affects the synthesis of L-lysine. In other words, a larger amount of L-lysine can be produced by increasing the concentration of NADPH in cell. Therefore, when an enzyme GapN, which does not inherently exist in E. coli, is introduced and expressed, there is a possibility of increase in the concentration of NADPH in cell. In addition, Valverde, F. et al. introduced a Clostridium acetobutylicum-derived gapN gene into E. coli to express the gene (FEBS Lett. 449, 153-158 (1999)).
However, conventionally, there has never been an example of developing a strain with improved L-lysine productivity by introducing the gapN gene into a L-lysine producing microorganism.
The inventors of the present invention has found that the productivity of a L-lysine producing strain can be improved by introducing a Clostridium acetobutylicum-derived gapN gene into the strain and completed the present invention.